<Francois]TY cas.
In "I need my dog walked", I believe there's an implicit agent: walked by someone. Or, to rephrase, "I need somone to walk my dog" -- but the later switch the focus to the agent, whereas the former keeps the focus on the dog. Is that correct?>
I guess it depends on one's perception of the whole thing. Some will say that "walked" in your construction, is a past participle, and others will claim it is an adejetive.
<In "I need my dog walking", I believe (the way I understand it) there's no agent involved. The focus is on the action: I want my dog to do this or that. Is that right?>
Could be, but then "walking" could be gerundive.
The gerundive (mainly found in Latin) "... does not refer to the completion of an activity the way a passive verb does, it does not have an agent in the true sense."
Following this logic, I've a hard time figuring out "I need my son spanking" or "I need my shirts ironing". Your discussion on "I need X Y-ing by six" puzzles me even more. >
Remember here that we are trying not to judge things too much from a Standard English viewpoint. The rules of Standard English are one thing, and rules for some
regional uses may not be the same.
<Why is "I need my shirts ironing"
be correct while "I need my shirt ironing by six" is wrong?>
"The adverbial "by six" states that something must be completed by a
specified time. In my "I need X doing", I feel there could be a focus upon the pending nature of something or... a focus on the action as being in process (incomplete) at an
unspecified time in the future.
The former case, i.e.
pending actions at the momnet of speaking fits well with the gerundive nature of "ironing".
"The gerundive expresses obligation, not tense."
<In both cases I would object (being a
ESL speaker) that shirts don't iron themselves (though that would be fairly convenient).>
That's fine, because you do that from a Standard English viewpoint, but there's a whole world of English usage beyond the
ESL and Standardists' classroom.
M56
Re: need explaining 
(yes, I've read the whole thread)
M56 started this discussion with, does anyone see an aspectual difference between:
Linear Mode
